I had a Hinatomotchi, (The fireball), and I let it's hearts drop down once.. I also sped the time up, and it pooped constantly, and stayed with it for only a few second, (I clean up immeadiately). xD
It became an elder female along with my other tama, who's a male, and they had babies. Guess what /they/ were?
Both were Bill! (Oyajtchi or what ever. The one with a ponytail. ^^)